Morphology-based tissue analyses comprise a critical approach for understanding disease mechanisms in animal models of arthritis. Recognizing that superior histologic preparation of rodent tissues for morphometric analysis requires a high degree of technical skill and experience, we have established a dedicated morphology core to facilitate the arthritis-focused studies in this submission. The functions of this morphology core include: i) harvest, preparation and sectioning of tissue for subsequent analysis; ii) histochemical, immunofluorescence and immunohistochemical staining of experimental tissues; iii) microscopy and imaging equipment for analysis and presentation;and iv) technical consultation and literature to aid in histomorphometric-based experimental design. The capabilities of the arthritis core will contribute to achieving the program objectives including histologic identification and quantification of synovial cellular lineages, quantification of pathologic features in synovial tissue (lining hyperplasia, leukocytic infiltration, bone and cartilage destruction) and quantification of synovial tissue extracellular matrix deposition and composition. All four projects in this submission incorporate histologic analysis of arthritic mouse tissues in their experimental design.